This application claims the priority of German Patent Application, Serial No. 100 25 597.3, filed May 24, 2000, pursuant to 35 U.S.C. 119(a)-(d), the disclosure of which is incorporated herein by reference.
The present invention relates to a device and method for charging a plasticizing unit of an injection molding machine, preferably a ram-type compactor for moist polyester.
Typically, a charging device of a type involved here includes a feed pipe which is connected to a plasticizing unit and supports the lower end of a compaction cylinder. The upper end of the compaction cylinder is received in a retaining flange which is securely mounted to the feed pipe. Displacement rails are arranged at a distance to the retaining flange for allowing conjoint movement of a compaction ram with a piston and cylinder unit and a storage container by means of a drive unit alternately between a first position in which the compaction ram is aligned flush with the compaction cylinder and the storage container is ready for receiving new material, and a second position in which the storage container is aligned flush with the compaction cylinder for discharge of material into the compaction cylinder.
During a material change, measures have to be taken to remove residual material still present in the feed pipe of the charging device. Hereby, access to the feed pipe for cleaning purposes becomes problematic because the feed pipe can be reached only via the retaining flange and the compaction cylinder when the compaction ram is drawn. Accessibility is further complicated by the fact that the compaction ram can be moved out of the compaction cylinder only to a limited degree, so that accessibility into the interior of the compaction cylinder is already obstructed.
It would therefore be desirable and advantageous to provide an improved charging device which obviates prior art shortcomings and which is simple in structure while yet provides easy access to the feed pipe to permit a rapid and reliable cleaning action during a material change.
According to one aspect of the present invention, a device for charging a plasticizing unit of an injection molding machine, in particular ram-type compactor for moist polyester, includes a feed pipe constructed for connection to the plasticizing unit, a compaction cylinder having a lower end supported by the feed pipe and an upper end, a storage container receiving material for introduction into the compaction cylinder, a compaction ram constructed for movement into the compaction cylinder, a retaining flange securely supported by the feed pipe and receiving the upper end of the compaction cylinder, a drive unit for moving the compaction ram and the storage container between a first position in which the compaction ram is in alignment with the compaction cylinder for allowing the compaction ram to compress the material in the compaction cylinder, while the storage container can be charged with new material, and a second position in which the storage container is in alignment with the compaction cylinder, and a coupling unit for linking the compaction cylinder to the compaction ram.
The present invention resolves prior art problems by detachably connecting the compaction cylinder with the compaction ram to provide a structural unit that can be moved away from the feed pipe to create access thereto for cleaning purposes.
According to another feature of the present invention, the coupling unit may include at least one coupling piece which is swingably mounted to the upper end of the compaction cylinder and selectively secureable to the retaining flange and an upper end of the compaction ram.
According to another feature of the present invention, the coupling piece may be secured to the compaction cylinder and the retaining flange by a screwed connection.
According to another feature of the present invention, the coupling piece may be lockable like a ratchet in a recess in the compaction ram.
According to another aspect of the present invention, a method of charging the plasticizing unit of an injection molding machine, includes the steps of moving a compaction ram and a storage container between a first position in which the compaction ram is in alignment with a compaction cylinder for allowing the compaction ram to compress material in the compaction cylinder, while the storage container can be charged with new material, and a second position in which the storage container is in alignment with the compaction cylinder for discharge of new material into the compaction cylinder, wherein for cleaning purposes the compaction cylinder is coupled with the compaction ram to form a structural unit which can be pulled upwards, and for assuming the operating position the structural unit is pushed downwards and the compaction cylinder is decoupled from the compaction ram.
According to another feature of the present invention, the compaction cylinder may be coupled in the operating position with a retaining flange which is securely supported by the feed pipe.